It is advantageous to have tough and ductile polymeric materials, for example, Ultrahigh Molecular Weight Polyethylene (UHMWPE), for total joint implants without sacrificing oxidative stability and wear resistance. Wear resistance can be improved by cross-linking. However, crosslinking reduces the toughness and ductility of the material. Therefore, it is desirable to have a method to increase toughness and ductility of wear and oxidation resistant polymeric material.
Various methods of making cross-linked polymeric materials are known in the field. Saum et al. (U.S. Pat. No. 6,316,158) described melting and subsequent radiation crosslinking of UHMWPE to increase ductility substantially through an increase in elongation at break. However, Saum et al. suggested not to using antioxidants in this process. The UHMWPE preform material used by Saum et al. does not contain antioxidants, as they believed that the presence of antioxidant may cause adverse effects in medical applications.
This application describes methods and approaches not found in the field for making cross-linked, wear and oxidation resistant, tough and ductile polymers, and materials used therein.